how thick of aluminum do you want to “machine”? Generally speaking the thinner the better
6061 aluminum is the easiest to machine and is available in 1/8" or thicker pieces, I have never seen it in thinner sheets. 5052 is ok, and 3003 alloy is horrible to machine; tends to get stuck in the router bit. only single upcut flutes shoudl be used
I would not try to cut anything thicker than 1/8" aluminum and would only recommend 6061 or 5052 is used, which is about $125 to $175 a 4x8’ sheet.
Previous poster is right, the “metal maslow” is named because the sled is metal, not because it was designed to cut metal per say. we are aiming to ship mid april to late april and will be taking initial orders soon.